Dissociating context and space within the hippocampus: effects of complete, dorsal, and ventral excitotoxic hippocampal lesions on conditioned freezing and spatial learning

Behav Neurosci. 1999 Dec;113(6):1189-203. doi: 10.1037/0735-7044.113.6.1189.


Rats with complete excitotoxic hippocampal lesions or selective damage to the dorsal or ventral hippocampus were compared with controls on measures of contextually conditioned freezing in a signaled shock procedure and on a spatial water-maze task. Complete and ventral lesions produced equivalent, significant anterograde deficits in conditioned freezing relative to both dorsal lesions and controls. Complete hippocampal lesions impaired water-maze performance; in contrast, ventral lesions improved performance relative to the dorsal group, which was itself unexpectedly unimpaired relative to controls. Thus, the partial lesion effects seen in the 2 tasks never resembled each other. Anterograde impairments in contextual freezing and spatial learning do not share a common underlying neural basis; complete and ventral lesions may induce anterograde contextual freezing impairments by enhancing locomotor activity under conditions of mild stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Conditioning, Classical / drug effects
  • Conditioning, Classical / physiology*
  • Excitatory Amino Acid Antagonists / administration & dosage
  • Fear / drug effects
  • Fear / physiology*
  • Hippocampus / drug effects
  • Hippocampus / injuries
  • Hippocampus / physiology*
  • Immobilization / physiology*
  • Male
  • Maze Learning / physiology*
  • Microinjections
  • N-Methylaspartate / administration & dosage
  • Orientation / physiology*
  • Rats
  • Rats, Inbred Strains
  • Time Factors


  • Excitatory Amino Acid Antagonists
  • N-Methylaspartate